How To Connect An Ac Power Filter

Question

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In that location are many different arrangements of Line filters designed for grid input to target device. The in a higher place is only a few. Others used cascaded CM chokes with a midpoint filter.

I run into a few problems in your setup.

Do not connect dark-green to Neutral. Grn/Yel is always Globe ground.
Do not connect Neutral to your ESD cablevision on your workbench.
The filter volition not do its job if y'all connect the Grn/Yel Earth Ground wire to Neutral.
Do not use a line filter designed for high voltage lower current to the output of your transformer which is lower voltage, high current. PUT IT ON THE 120Vac ( or 240Vac) side. Merely low voltage depression electric current is OK.

My hunch is your 24Vac load was excessive due to the cadet converter and caused some resonance with the line filter on your wallwart.

I can only make an experienced guess, because I exercise not take your measurements or schematics.

Re-wire the filter with a iii pivot plug and socket and add heatshrink to insulate exposed solder joints.
Follow my advice in points i~five
If you ever notice such voltage loss in future, alert current is excessive and you should use an appropriately rated inline input fuse or PTC ( in an enclosure equally it gets hot when activated.)

Conclusion

The Full-Bridge cap DC to Buck DC-DC regulator caused thermal issues for your brick, possibly exacerbated by the line filter. The line filter installation info on the web was never searched.

Postal service Mortem

Afterward looking at the spec link for transformer rated at 20VA 24V , once again this must be derated when used with an diode bridge cap load to no more than 15VA. Then the DC–DC converter should soft start and run NO MORE than the same, I conclude you accept the incorrect transformer VA rating for the job or a bad startup load.

All transformers are rated @ Vout at max VA and expected to driblet x% Vac at this load from no load . When you lot drib 50% every bit in your measured voltage, that should have been your clue information technology was going to smoke. The fine wire primary cannot dissipate the rut fast plenty then it is chosen to drop no more than 10% including secondary losses. Thus drawing perhaps 5x the rated load dropping another 50% implies your load was the cause of the smoke. You must verify your design start surge current with sense R's or ammeter to ensure information technology has a soft commencement past adding ICL's to limit the starting electric current enable a holding current. These are cheap from Digikey.